Wound golf balls are the preferred ball of more advanced players due to their spin and feel characteristics. Wound balls typically have either a solid rubber or fluid-filled center around which a wound layer is formed, which results in a wound core. The wound layer is formed of thread that is stretched and wrapped about the center. The wound core is then covered with a durable cover material, such as a SURLYN.RTM. or similar material, or a softer "performance" cover, such as Balata or polyurethane. Examples of such balls are disclosed in U.S. Pat. Nos. 4,244,855; 5,020,803; 5,033,749; 5,496,034; and 5,683,311.
Wound balls are generally softer and provide more spin than solid balls, which enables a skilled golfer to have more control over the ball's flight and final position. Particularly, with approach shots into the green, the high spin rate of soft covered, wound balls enables the golfer to stop the ball very near its landing position. In addition, wound balls exhibit lower compression than non-wound balls. Although the higher spin rate exhibited by wound balls means wound balls generally display shorter distance than hard covered non-wound balls, the advantages of wound constructions over non-wound ones are more related to targeting or accuracy than distance.
The United States Golf Association (USGA), the organization that sets the rules of golf in the United States, has instituted a rule that prohibits the competitive use in any USGA sanctioned event of a golf ball that can achieve an initial velocity of 76.2 meters per second (m/s), or 250 ft/s, when struck by a driver with a velocity of 39.6 m/s, i.e., 130 ft/s (referred to hereinafter as "the USGA test"). However, an allowed tolerance of 2 percent permits manufacturers to produce golf balls that achieve an initial velocity of 77.7 m/s (255 ft/s).
Players generally seek a golf ball that delivers maximum distance, which requires a high initial velocity upon impact. Therefore, in an effort to meet the demands of the marketplace, manufacturers strive to produce golf balls with initial velocities in the USGA test that approximate the USGA maximum of 77.7 m/s or 255 ft/s as closely as possible. Manufacturers try to provide these balls with a range of different properties and characteristics, such as spin.
To meet the needs of golfers with various levels of skill, golf ball manufacturers are also concerned with varying the level of the compression of the ball, which is a measurement of the deformation of a golf ball under a fixed load. A ball with a higher compression feels harder than a ball of lower compression. Wound golf balls generally have a lower compression which is preferred by better players. Whether wound or non-wound, all golf balls become more resilient (i.e., have higher initial velocities) as compression increases. Manufacturers of both wound and non-wound construction golf balls must balance the requirement of higher initial velocity from higher compression with the desire for a softer feel from lower compression.
Therefore, golf ball manufacturers are continually searching for new ways in which to provide wound golf balls that deliver good performance for golfers.